1. Field of the Invention
This invention relates to a seal part for sealing a developer and a developing device having the same. This developing device is preferably used in an image forming apparatus such as an electrophotographic copier or an electrophotographic printer, or a process cartridge detachably attachable to the main body of the image forming apparatus.
The electrophotographic image forming apparatus is an apparatus for forming an image on a recording medium by the use of the electrophotographic image forming method. Examples of the electrophotographic image forming apparatus include, for example, electrophotographic copiers, electrophotographic printers (such as laser beam printers and LED printers), facsimile apparatuses and word processors.
Also, the process cartridge refers to at least one of charging means, developing means and cleaning means and an electrophotographic photosensitive member integrally made into a cartridge which is detachably attachable to the main body of the image forming apparatus.
2. Related Background Art
In the electrophotographic image forming apparatuses using the electrophotographic image forming process, it is known to use a process cartridge system whereby an electrophotographic photosensitive member and process means for acting on the electrophotographic photosensitive member are integrally made into a cartridge detachably attachable to the main body of the image forming apparatus. According to this process cartridge system, the maintenance of the apparatus can be done by a user himself without resorting to a serviceman and therefore, operability could be markedly improved. So, this process cartridge system is widely used in the electrophotographic image forming apparatuses.
Also, the developing cartridge system whereby for example, developing means of the process means except the electrophotographic photosensitive member is integrally made into a cartridge detachably attachable to the main body of the image forming apparatus is adopted in multicolor electrophotographic image forming apparatuses, and has an effect similar to that described above.
In the electrophotographic image forming apparatus of the electrophotographic type (hereinafter referred to as the image forming apparatus), it is practiced to visualize an electrostatic latent image formed on an image bearing member as a toner image by a developing device.
As such a developing device, various dry monocomponent developing devices have been proposed and put into practical use. In any of these developing devices, however, it is difficult to form a thin layer of a toner which is a monocomponent developer on a developer bearing member.
However, now that improvements in the resolving power, definition, etc. of image are required, the development of a method of and an apparatus for forming a thin layer of a toner is requisite, and several measures for this have been proposed.
For example, as disclosed in Japanese Patent Application Laid-Open No. 54-43038, an elastic blade or the like as a regulating member formed of such a material as a metal or rubber is made to abut against a developing sleeve which is a developer bearing member, and a toner is passed through the abutting portion between the elastic blade and the developing sleeve and is regulated, whereby a thin layer of the toner is formed on the developing sleeve and sufficient triboelectricity is imparted to the toner by the friction in the abutting portion.
In this case, when a nonmagnetic toner is to be regulated by the above-described elastic blade, a toner supplying member for supplying the toner onto the developing sleeve becomes discretely necessary. This is because in the case of a magnetic toner, the toner can be supplied onto the developing sleeve by the force of a magnet in the developing sleeve, but in the case of the nonmagnetic toner, the supply of the toner cannot be effected.
As an example, there is a case where a toner supplying roller formed of urethan or the like is used as the toner supplying member. The toner supplying roller comprises a metal shaft and a roller portion of urethane formed thereon, is mounted on a developing container so as to be in contact with the developer bearing member, is supported by bearing members mounted on the opposite ends of the developing container, and is rotated so that the peripheral surface of that portion thereof which is opposed to the direction of movement of the peripheral surface of the developer bearing member may be moved in the opposite direction. The developing container supporting a developing member has its interior and exterior partitioned by a partition member, and the space between the partition member and the developing member is sealed.
A conventional method of mounting the toner supplying roller will now be described with reference to FIG. 11 of the accompanying drawings. In FIG. 11, when mounting a toner supplying roller 9R on a developing container 26, one shaft 9jR of the toner supplying roller 9R is passed into an aperture portion 26aR formed at one end of a wall portion 26a which is a partition member for the interior and exterior of the developing container 26, and the other shaft 9jF of the toner supplying roller is put into a cut-away portion 26aK formed at the opposite side to the aperture portion 26aR of the developing container 26, and the shaft 9jF of the toner supplying roller 9R is passed into an aperture portion 25a provided in a filling member 25 filling the cut-away portion 26aK, and the filling member 25 is attached to the developing container 26 to thereby fill the cut-away portion 26aK.
Thereafter, as shown in FIG. 11, shaft seal members 28 formed of felt or the like are fitted onto the shafts 9jF and 9jR at the opposite ends of the toner supplying roller 9R, and lastly bearing members 27F and 27R are assembled to the shafts from the opposite sides, whereby the toner supplying roller 9R is supported. In this construction, the shaft seal members 28 of felt may sometimes be deformed and therefore, auxiliary shaft seals such as oil seals 29 as auxiliary means for the shaft seal members 28 are assembled to the toner supplying roller shaft supporting portions 27Fj and 27Rj of the bearing members 27F and 27R on the opposite sides.
The relation between the filling member 25 and the toner supplying roller shaft 9jF is such that as shown in FIG. 11, the aperture portion 25a provided in the filling member 25 and the toner supplying roller shaft 9jF are not at all in contact with each other, but have a gap therebetween.
In recent years, however, the main body of the image forming apparatus tends to become lower in cost and smaller in size and along therewith, the necessity of lower cost and smaller size has also increased in the process cartridge.
In the above-described example of the conventional art, however, besides the filling member filling the cut-away portion when the toner supplying roller is incorporated into the developing container, a plurality of seal members such as the shaft seal members and the auxiliary seals for the shaft seals in which the bearing members of the toner supplying roller are provided become necessary and cause an increase in cost and also, provision must be made of spaces for incorporating those seal members therein, and this has hindered the downsizing of the process cartridge.
The present invention solves the above-noted problem and an object thereof is to provide a method of constructing the seal of a rotary member extending through a partition member at a low cost and with a saved space, and to provide a seal part and a developing device directed to the same purpose.
Another object of the present invention is to provide a seal part and a developing device of which a portion of the frame is formed by the seal part.